Abstract The public health impact of posttraumatic stress disorder (PTSD) is enormous. PTSD greatly increases the risk of suicidal ideation and attempts as well as the likelihood of developing multiple, often severe comorbid disorders. Although several evidence-based treatments for PTSD have been found to be effective in community settings, patients who are acutely suicidal and/or have severe comorbid disorders are typically excluded from these treatments. The Dialectical Behavior Therapy Prolonged Exposure (DBT PE) protocol, which is designed to be integrated into standard Dialectical Behavior Therapy (DBT) to treat PTSD among suicidal and multi-diagnostic patients, has shown evidence of efficacy in a randomized clinical trial (RCT) conducted in a research setting as well as effectiveness in several non-randomized trials conducted in community settings. In particular, the integrated DBT+DBT PE treatment has been shown to significantly improve PTSD, suicidal and self-injurious behavior, comorbid psychological distress, and psychosocial functioning. However, a large-scale RCT is needed to rigorously examine the treatment?s effectiveness in community practice settings. In addition, an implementation model comprised of a 4-day workshop followed by up to 32 hours of team-based expert consultation with session review and feedback has shown promise in facilitating adoption of the DBT PE protocol among community clinicians. However, post-workshop consultation with session review is resource-intensive, and there is a lack of research to guide decisions about the optimal dose and type of consultation to provide. The present project aims to extend this prior work by conducting a hybrid type 2 effectiveness-implementation trial among community-based agencies that provide standard DBT to adolescents and/or adults. The project will be conducted in collaboration with the Missouri Department of Mental Health and will enroll a minimum of 224 clinicians and 170 patients. The project has two co-primary aims: (1) Clinical Effectiveness (Aim 1) is to conduct a cluster randomized trial to evaluate the effectiveness of DBT+DBT PE versus DBT as usual on changes in patient-level PTSD, suicidal thoughts and behaviors, global symptom severity, and functional impairment, and (2) Implementation Evaluation (Aim 2) is to use a sequential multiple assignment randomized trial design to evaluate how long to provide consultation and whether to augment it with session review based on early response to optimize changes in clinician-level adoption, penetration, and sustainment. Mechanisms of effectiveness and implementation outcomes as well as multi- level predictors of implementation outcomes will be evaluated. This research has the potential to significantly impact public health by increasing access to effective PTSD treatment for some of the most high-risk and severe consumers of mental health services while simultaneously yielding generalizable knowledge about how best to reduce the resource-intensiveness of post-workshop consultation without sacrificing outcome.